Doug -
This is how I remember it too. In fact I just listened to a Grant presentation the other night whereas it was stated that Buckner mearly did what you said, basically speaking on Grant's good to pay, not actually loaning him the money.
In regards to Buckner's and Pillow's misgivings, I believe more of that had to do as a result of what happened after the Mexican war while Pillow was trying to climb the political ladder, while bad mouthing General Scott during their time in the Mexican War, when Buckner was sending letters to the Nashville Paper, signed as the "citizen" I believe speaking of Pillow's lack of ability and his lying ways. It was pretty much assumed that it was Buckner writing the letters that helped keep Pillows career from gaining momentum. Needless to say, when Pillow and Buckner met at Donelson, it was not mutually pleasant.
John Walsh